The present invention relates generally to the data processing field, and more particularly, relates to a method and apparatus for determining the tribology for a head/disk interface.
Modern disk drives are becoming more sophisticated with lower flyheight, higher areal recording densities, and faster rotational spindle velocities. The lower flyheight requires more information about the tribology of the many head/disk interfaces in the disk drive. This information generally must be obtained in an in-situ way and must be computational tractable within the onboard computing facilities of the disk drive.
A need exists for an improved method and apparatus for determining the tribology for a head/disk interface.
As used in the present specification and claims, the term transducer head should be understood to include a slider with an attached write head and read head, such as a MR head. Typically, the MR head element is recessed and a rear pad of the slider makes the contact with a disk surface. As used in the present specification and claims, the term cylinder should be understood to mean a track.
A principal object of the present invention is to provide a method and apparatus for determining the tribology for a head/disk interface. Other important objects of the present invention are to provide such method and apparatus for determining the tribology for a head/disk interface substantially without negative effect and that overcome many of the disadvantages of prior art arrangements.
In brief, a method and apparatus are provided for determining the tribology for a head/disk interface in a direct access storage device (DASD). A readback signal is obtained from a predetermined cylinder. The readback signal is sampled to provide a readback sampled sequence. The readback sampled sequence is summed to store a sum for each data sector of a plurality of data sectors in said predetermined cylinder. Predetermined discrete Fourier transform (DFT) components are calculated for the data sector sums. A harmonic ratio is calculated utilizing the calculated predetermined DFT components. The calculated harmonic ratio is compared with a predefined threshold value to identify the tribology for a head/disk interface.
In accordance with features of the invention, each of a plurality of predetermined heads is sequentially positioned on each of a plurality of predetermined cylinders for obtaining a readback signal. A plurality of predefined threshold values are provided for the plurality of predetermined heads and the plurality of predetermined cylinders. Zeroth and first discrete Fourier transform (DFT) components are calculated for the data sector sums. The harmonic ratio is calculated by dividing the magnitude of the zeroth DFT component by the magnitude of the first DFT component.